The Europa League - the Champions League's eccentric, overshadowed younger sibling - can be a true delight if you just get to know it.

The mammoth group stage wrapped this week and the bracket for the round of 32 is now set. With 144 games in the opening salvo, you may have missed some intriguing storylines. Here are some of the most notable.

Low seeds advancing

What do AC Milan, Marseille, Anderlecht, and Besiktas have in common? Each has European pedigree but is out of the Europa League already, and replacing them are a raft of previously underwhelming sides. While Marseille finished bottom of Group H with one point from six games, Eintracht Frankfurt, in only their third European campaign since the mid-1990s, recorded a remarkable six wins from six.

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Frankfurt are one of eight teams from Pots 3 or 4 of the draw to progress, along with Real Betis, Slavia Prague, Dinamo Zagreb, BATE Borisov, Malmo, Rennes, and FC Zurich. When the draw for the first knockout round, which will begin action in mid-February, takes place on Monday, there will be some aspiring hopefuls mixed in with the big boys who also progressed or have dropped down from the Champions League.

British youngsters

The Europa League has been used as a testing ground for promising young players in the past and that trend has continued this year, nowhere more so than at Arsenal. Emile Smith Rowe became the first 21st century-born player to appear for the Gunners in their first match against Vorskla Poltava and the first to score for the club when he netted in the 3-0 win at Qarabag. Two months later, he bagged the opener at Vorskla in a game that also saw the first-ever senior goal from 19-year-old Joe Willock. Meanwhile, 19-year-old Charlie Gilmour, 18-year-old Zech Medley, and 17-year-old Bukayo Saka all made their senior professional debuts during the group stage.

Scottish progress

Though Scotland's two representatives experienced mixed fortunes in the group stage - Celtic squeezed into the last 32 by virtue of Rosenborg's late equalizer against RB Leipzig, whereas Rangers missed out - there was tangible progress from both. Rodgers' Bhoys beat Rosenborg home and away and also saw off Leipzig in Glasgow. Three wins from six were not only enough to see them through in second, but also propelled them to their most successful group-stage showing since 2012-13.

Gerrard's charges, meanwhile, had bright moments in their first group-stage campaign in eight years, most notably drawing 2-2 at Villarreal and beating Rapid Wien. In fact, the Gers went home having lost just two of their six games, each by a single goal. It's a sign that the blue side of Glasgow, given some much-needed stability in the immediate future, can compete once more in Europe.

Red Bull gives you wins

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In a peculiar quirk of the draw, German side Leipzig were pitted against their Austrian Red Bull counterparts Red Bull Salzburg. It was an interesting matchup for many reasons, not least the animosity felt by Salzburg fans in response to Leipzig's habit of pinching their sibling club's star players. Throw in Leipzig's fast-cash success in the Bundesliga and the wider Germany-Austria contention, and the first-ever competitive meetings between the teams did not disappoint.

In the first clash at Leipzig's Red Bull Arena on Matchday 1, the hosts came back from 2-0 down to tie it at 2-2 late on before Fredrik Gulbrandsen won it for the visiting Austrians in the 89th minute. The Norwegian would be the hero again in the return leg at Salzburg's own Red Bull Arena (imaginative names, these), scoring the only goal to extend his side's unbeaten record. Some 30 games into their season in all competitions, Salzburg are the only European top-flight team not to have lost a game in 2018-19.

Unbeaten records

Talking of undefeated streaks, some nine teams boasted unbeaten runs in the competition going into Matchday 6 on Thursday, and seven of those held true through the final round of fixtures. Frankfurt, for instance, in only their third European campaign since the mid-1990s, won all six of their group games in a tough pool containing Lazio and Marseille.

Elsewhere, Salzburg mirrored Frankfurt's impressive achievement in Group B, while Villarreal, Chelsea, Arsenal, Zagreb, and Betis all navigated the round-robin stage without suffering defeat. Seven of 24 progressed teams going six games unbeaten is an impressive feat, and those sides will likely fancy themselves against even the third-placed Champions League clubs dropping down. In home-and-away ties, good form and high confidence can be the deciding factors.